This invention relates to a liquid stabilizer composition, to a polyether polyol stabilized against degradation by the liquid stabilizer composition and to a polyurethane foam obtained from the stabilized polyether polyol. More particularly, the invention relates to the stabilization of polyether polyols employing a liquid stabilizer composition containing a mixture of mono- and di-alpha methyl styrenated diphenylamines and inhibiting scorch in flexible and semiflexible polyurethane foams made from the stabilized polyether polyols.
Substituted diphenylamines of the general formula: ##STR1## wherein at least one of R.sub.1, R.sub.2 and R.sub.3 is phenyl and at least one of R.sub.4, R.sub.5 and R.sub.6 is phenyl, the remaining R's being methyl, phenyl, p-tolyl, neopentyl or 2-phenylisobutyl, are disclosed in U.S. Pat. Nos. 3,452,056, 3,505,225, 3,649,690, 3,666,716, 3,751,472, 3,758,519, 3,781,361 and 3,944,492. Such substituted diphenylamines and their combinations are useful as antioxidants for the protection of polymers having relatively low olefinic unsaturation such as polyolefins and acrylonitrile-butadiene-styrene polymers and other polymers such as polyamides, polyesters and acetal resins and lubricant compositions. No mention is made in any of the foregoing patents of the use of such substituted diphenylamines as stabilizers for polyether polyols used in the production of polyurethane foams.
Czech Patent No. 261,547 discloses a stabilizer composition, useful as an antioxidant and heat stabilizer for rubber latexes, polyolefins, polyamides and oils, which consists of a mixture of from about 3 to about 55 weight percent of a mono-alpha methyl styrenated diphenylamine, i.e., 4-alpha, alpha-dimethylbenzyl diphenylamine which may be represented by the structural formula: ##STR2## and from about 45 to about 97 weight percent of a di-alpha methyl styrenated diphenylamine, i.e., 4,4'-bis-(alpha, alpha-dimethylbenzyl) diphenylamine which may be represented by the structural formula: ##STR3## Czech Patent No. 261,547 does not disclose the use of this mixture as a stabilizer for polyether polyols or for polyurethanes manufactured from such polyols.